Cold finishing of metal



Feb. 2, 1965 G. ZAVODNY, JR., ETAL 3,163,004

cow FINISHING OF METAL Filed May 11, 1962 Fla 1 GeargaZauudRg ,JZ Norman M Breyer Elli 0i 5. Nae/11 272001 INVENTORS United States Patent 3,168,004 COLD FINHSHENG 0F METAL George Zavodny, .lrx, and Norman N. Breyer, Chicago,

and Elliot S. Nachtman, Evanston, Ill, assignors to La Salle Steel Company, Hammond, Ind., a corporation of Delaware Filed May 11, 1962, Ser. No. 194,142 Claims. (Cl. 90-24) This invention relates to the cold finishing of metals and more particularly to the removal of surface metal from wire, bars, rods and the like metal structures of repeating cross-section in long lengths.

This application is an improvement over the copending application Serial No. 691,727, filed October 22, 1957, now abandoned, entitled Cold Finishing of Metal, which in turn is a continuation-in-part of Serial No. 615,328, filed October 11, 1956, Patent No. 3,055,102 issued September 25, 1962, and entitled Metal Finishing Means and Method for Use of Same.

In the copending application Ser. No. 615,328, filed October 11, 1956, description is made of a shaving tool in tandem arrangement with a draw die having the space in between filled with a lubricating liquid under atmospheric or superatmospheric pressure. The shaving tool operates to remove metal from the surface portions of the work in preparation of the work for advancement through the draw die to take a reduction in cross-sectional area as in a conventional cold finishing operation.

It has been found that with a great number of metals, as represented by hot rolled low, medium, or high carbon steels and alloy steels, heat treated steels, previously drawn or worked steels, and the like, the material being removed by the shaving tool builds up on the shaving edge of the shaving tool and that this built-up edge displaces the tool as the shaver of the material being advanced therethrough. The built-up edge represents workpiece material that has become strain hardened by the work performed in the removal of the chip. The strain hardened material appears to become welded onto the edge of the shaving tool in such a manner that it is this material that does the shaving of the softer work material advanced through the shaving tool. Because of the buildup on the shaving edge, it becomes difiicult to hold the metal removal to the desired tolerances. More often more metal is removed from the surface of the work than was intended to be removed by the tool. In addition, the material built up on the edge of the shaving tool periodically leaves the tool and remains welded onto the surface of the work. As a result, an inferior and undesirable product having poor surface finish and poor dimensional characteristics is often secured, both before and after the work is advanced through any subsequent reduction die such as a drawing or extrusion die. Thus, it is an object of this invention to produce and to provide a method whereby the built-up or work material on the edge of the shaving tool can be minimized and preferably avoided and it is a related object to produce an apparatus for use in same.

More specifically, it is an object of this invention to provide a means whereby a shaving tool can be employed to improve the dimensional control of the metal removed by the shaving tool; in which metal is shaved cleanly and smoothly from the surface of the work without waviness on the surface of the work and without the work wandering from one side to the other in the shaving tool; in which the metal is shaved from the work without chattering and wherein good stability is maintained throughout the operation; in which metal removal is achieved in a simple and efficient manner with a minimum amount of labor and equipment; and in which the work material "ice does not build up on the shaving edge of the shaving tool to displace the shaving edge as a means for the removal of metal from the surface of the work.

These and other objects and advantages of this invention will hereinafter appear and for purposes of illustration, but not of limitation, an embodiment of the invention is shown in the accompanying drawing, in which:

FIG. 1 is a diagrammatic elevational view, partially in section, of a tool assembly embodying the features of this invention; and

FIG. 2 is a view similar to that of FIG. 1, showing a modification in the shaving tool.

in accordance with the practice of this invention, the build-up of work material on the shaving edge of the tool is avoided or minimized when the metal being removed is heated sufiiciently during removal to soften the metal to minimize and preferably avoid the strain hardness which otherwise is normally introduced into the metal by deformation performed during shaving at Work advancement speeds, usually lower than about 200 feet per minute. These conditions can be achieved in a simple and efiicient manner by causing the material being shaved from the surface of the work to be heated during shaving to the temperature near or preferably within or corresponding to the hot working region for the metal to be worked.

For most steels commonly subjected to cold finishing processes, this temperature will be above 700 F. and preferably above 1100 F. Corresponding temperatures can be determined for other steels and metals.

It is an important concept of this invention to achieve the desired temperature build-up in the chip or metal being removed at a rate of work advancement usually lower than about 200 feet per minute, by preheating the Workpiece and the metal to be removed to a temperature in excess of 250 F. but below the lower critical temperature for the metal prior to removal of the surface metal by the shaving tool. When the workpiece or the metal to be removed is thus preheated, the additional heat required to raise the metal being removed to a temperature near or preferably within or corresponding to the hot working region for the metal to be worked, and thereby avoid or minimize a build-up of metal on the shaving edge, is achieved by the work performed during the removal of the surface metal by the shaving tool. It is also possible to achieve the desired final temperature build-up in the chip or metal being removed at a rate of work advancement usually lower than about 200 feet per minute by heating with external means the workpiece or metal to be removed during removal, rather than prior to removal by the shaving tool. Whatever rate is used, the end result should be that the combined heat of the external source and the work performed in metal removal should add up to the desired final temperature build-up in the chip or metal being removed.

It will be apparent from the foregoing that the linear speed at which the work is advanced through the shaving tool is dependent upon the temperature build-up from the external heat means. It will also be apparent that there are a great variety of combinations of these linear speeds and external heat temperature build-ups which will achieve the desired final temperature build-up in the metal being removed. Not so apparent is that certain single external heat temperature build-ups will produce the desired results with certain single designs of shaving tool over wide ranges of linear speeds, depths of surface removal, and metal grades. This is an important concept of this invention in that the practice related to by this invention is much simplified.

For example, for all of the many grades of steel and for all of the many depths of surface removal within the range of 0-15 percent of the workpiece cross-section that the applicants have shaved in accordance with the concepts of this invention, they have. found that just a very few external heat temperature build-ups and designs of shaving tool have produced the desired results at all linear workpiece speeds within the range of 1-200 feet per minute. The exact external heat temperature build-up and design of shaving tool which will give the desired results over such wide ranges of linear speeds and depths of surface removal for any or similar grades of metals is dependent on the metal grades to be worked, the depths of surface removal required, and the speeds and power available, but they can easily be found by applying the principles of practice disclosed in this invention.

The design, or geometry and material, of the shaving tool is considered to be extremely important to obtain the desired results.

The geometry of the shaving tool is also particularly important to keep the work from wandering during passage through the shaving tool. the geometry is the rake angle. For best results, the rake angle should have a value of 70 to +20 and preferably 5 to +5. Also important is the clearance angle. For best results, the clearance angle should have'a value of 15 to' +15 and preferably --2 to +2. The best possible combination of these rake and clearance angles is dependent on the particular application.

In FIGS. 1 and 2 in the drawing, the shaving tool, work, and surface removed are identified by the numerals 1 and 1, 2 and 2', and 3 and 3", respectively. An example of the positive rake angle is identified by the numeral 4 in FIG. 1. An example of the negative rake angle is identified by the numeral 4' in FIG. 2. An example of the positive clearance angle is identified by the numeral 5 in FIG. 2. An example of the negative clearance angle is identified by the numeral 5 in FIG. 1.

'With reference to the material or grade of the shaving tool, use should be made of materials which, at the aforementioned final temperature build-ups required in the metal being removed, have resistance to deformation and to the aflinity to weld to the metal of the work or the metal being removed. For shaving most steel workpieces, such materials include certain sintered carbides, oxides, borides, silicides, or the like, and do not include any of the tool steels or the tool steels lightly coated with other materials.

In the aforementioned applications Serial Nos. 691,727

and 615,328, the shaving operation for removal of surface metal is described as being carried out While in combination with a draw die either in advance of the shaving tool to guide the work into the shaving tool and/or to the rear of the shaving tool to effect reduction in crosssectional area of the work as it is advanced from the shaving tool to the die. It has been found that while the combination of draw and/or guide dies with the shaving tool is desirable in systems where the workpiece is cold finished at about ambient temperatures, as in the aforementioned application Ser. No. 615,328, the combination is many times not desirable in systems where use is made of external heat means, as in this and the aforementioned application Ser. No. 691,727. Serious galling more often than not occurs in the dies, particularly when a final draw die is used and the entire workpiece cross-section, or a substantial part of it below the depth of surface removal, is heated by external means nearer to the upper critical temperature for the metal being worked. Also, in many instances, reductions in dies are neither desired nor required. Therefore, it is an important concept of this invention not to employ guide and/or draw dies in continuous operation with the shaving tool.

It will be apparent from the foregoing that we have provided a simple and efiicient means for the removal of unwanted metal from the surface of a workpiece of repeating cross-section in long lengths. Although the prin- The most important part of lengths of repeating cross-section, the steps of advancing ciples and practices disclosed in this invention have been particularly cited or implied with reference to steels commonly subjected to cold finishing processes, to linear work speeds below about ZOQfeet per minute, to solid crosssection workpieces, to round cross-section workpieces, to removals along the entire periphery of the workpiece cross-section, to removals on outer surfaces of the workpiece, to stationary shaving tools, to one-piece shaving tools, to one shaving tool in use at one time, and to advancing the work relative to the shaving tool, it will also be apparent that this invention will have application to other metals, to linear work speeds above about 200 feet per minute, to hollow cross-section workpieces, to shapes of workpiece cross-section other than round, to removals along only parts of the periphery of the workpiece cross-section, to removals on the inside surfaces of hollow cross-section workpieces, to other than stationary shaving tools, to multi-piece shaving tools, to more than one shaving tool arranged in tandem, and to advancing the shaving tool relative to the workpiece, respectively.

It will be apparent that other changes may also be made in the details of construction, arrangement and operation without departing from the spirit of the invention, especially as defined in the following claims.

We claim:

1. In the process of removing surface metal from elongate workpieces of repeating cross-section, the steps of advancing the metal linearly through a shaving tool which completely encircles the workpiece for the removal of said surface metal, prior to metal removal, heating the metal tobe removed from the Work to a temperature within the range of 250 F. to the lower critical temperature for the metal, and maintaining the rate of advance- 'ment of the work through the shaving tool to cause the temperature of the metal being removed tobe raised to a final temperature nearpthe hot working region of the metal.

2. In the process of removing surface metal from 'elongate workpieces of repeating cross-section, the steps of advancing the metal Work linearly through a shaving tool which completely encircles the workpiece, heating the metal to be removed from the work to a temperature within the range of 250 F. to the lower critical temperature for the metal, and maintaining the rate of advancement of the work to cause the temperature of the metal being removed to be built up beyond the temperature to resoften the metal by an amount which greatly minimizes its being retained on the shaving edge of the shaving tool.

3. In the process of removing surface metal from elongate workpieces of repeating cross-section, the steps of advancing the metal work linearly through a shaving tool which completely encircles the workpiece, heating the metal to be removed from the workpieces to a temperature within the range of 250 F. to the lower critical temperature for the metal, and maintaining the rate of advancement of the work through the shaving tool to cause the metal being removed to be raised in temperature beyond the recrystallization temperature of the metal of which the work is formed.

4. In the precess of removing surface metal from steel the metal work linearly through a shaving tool which completely encircles the workpiece, heating the metal to be removed to a temperature within the range of 250 F. to

. the lower critical temperature for the steel, and maintaining the rate of advancement of the steel through the shaving tool at a speed sufiicient to cause the metal being removed to be raised in temperature to soften the steel.

5. The method as claimed in claim 4, in which the 7 length of steel is advanced through the shaving tool at a rate sufficient tocause the metal being removed to be raised to a temperature above 700 F.

6. The method as claimed in claim 4, in which the length of steel is advanced through the shaving tool at a rate suificient to cause the metal being removed to be raised to a temperature above 1100" F.

7. The method as claimed in claim 4, in which the shaving tool is formed with a rake angle of within the range of -70 to +20".

8. The method as claimed in claim 4, in which the shaving tool is formed with a rake angle of within the range of 5 to +5".

9. The method as claimed in claim 2, in which the shaving tool is formed with a clearance angle of within the range of 15 to +15.

10. The method as claimed inclaim 2 in which the shaving tool is formed with a clearance angle of within the range of 2 to +2".

11. The method as claimed in claim 2, in which the shaving tool is of a material selected from the group consisting of sintered carbides, oxides, borides, silicides and the like, which, at the final temperature build-ups in the metal being removed avoids or minimizes shaving edge deformation and welding to the metal being removed or to the work.

12. In the process of removing metal from workpieces of repeating cross-section in long lengths, the steps of advancing the metal work linearly through a shaving tool which completely encircles the workpiece, heating with external means the work in advance of passage through said tool whereby the metal to be removed is heated to a temperature within the range of 250 F. to the lower critical temperature for the metal, and maintaining the rate of advancement of the work to cause the temperature of the metal being removed to be raised to the temperature near the hot working region of the metal of which the work is formed.

13. In the process of removing metal from workpieces of repeating cross-section in long lengths, the steps of advancing the metal work linearly through a shaving tool which completely encircles the workpiece heating with external means the work during removal by said tool whereby the metal being removed is heated to a temperature within the range of 250 F. to the lower critical temperature for the metal, and maintaining the rate of advancement of the work to cause the temperature of the metal being removed to be raised to the temperature within the hot working region of the metal of which the work is formed.

14. In the process of removing metal from workpieces of repeating cross-section in long lengths, the steps of advancing the metal work linearly through a shaving tool which completely encircles the work, said tool being formed with a rake angle between and +20 and with a clearance angle between 15 and +15 heating the work in advance of passage through said tool w ereby the metal to be removed is heated to a temperature within the range of 250 F. to the lower critical temperature for the metal, and maintaining the rate of advancement of the work to cause the temperature of the metal being removed to be raised to the temperature near the hot working region of the metal of which the work is formed.

15. A method in accordance with claim 14 wherein the rake angle of said tool is between 5 and +5 and wherein the clearance angle of said tool is between 2 and +2.

References Cited in the file of this patent UNITED STATES PATENTS 2,233,928 Weaver Mar. 4, 1941 2,600,453 Weingart June 17, 1952 2,679,680 Hanks June 1, 1954 2,972,287 Rusinoff Feb. 21, 1961 FOREIGN PATENTS 562,016 Canada Aug, 19, 1958 

1. IN THE PROCESS OF REMOVING SURFACE METAL FROM ELONGATE WORKPIECES OF REPEATING CROSS-SECTION, THE STEPS OF ADVANCING THE METAL LINEARLY THROUGH A SHAVING TOOL WHICH COMPLETELY ENCIRCLES THE WORKPIECE FOR THE REMOVAL OF SAID SURFACE METAL, PRIOR TO METAL REMOVAL, HEATING THE METAL TO BE REMOVED FROM THE WORK TO A TEMPERATURE WITHIN THE RANGE OF 250*F. TO THE LOWER CRITICAL TEMPERATURE FOR THE METAL, AND MAINTAINING THE RATE OF ADVANCEMENT OF THE WORK THROUGH THE SHAVING TOOL TO CAUSE THE TEMPERATURE OF THE METAL BEING REMOVED TO BE RAISED TO A FINAL TEMPERATURE NEAR THE HOT WORKING REGION OF THE METAL. 